lwip/linux: Add lwip support for networking component under linux

linux/lwip: Wrap some IO posix functions
* to workaourd the FreeRTOS EINTR issue (when building without lwip)
* to correctly choose the sub-system based on fd (when building with
lwip) -- passing control to either linux/system or to lwip
This commit also addapts tapio-if to provide DHCP client by default and
configurable settings for static IP

examples/protocols/linux_stubs/esp_stubs/include/esp_netif.h

@@ -8,4 +8,12 @@
 #include <ifaddrs.h>
 #include "esp_err.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 esp_err_t esp_netif_init(void);
+
+#ifdef __cplusplus
+}
+#endif